1. Field of the Invention
The present invention relates to electroacoustic transducers for converting an acoustic pressure into an electric voltage. It relates more particularly to microphones in which the conversion of an acoustic vibration into an electric voltage is provided by a piezoelectric polymer vibrating element.
2. Description of the Prior Art
Different models of electroacoustic transducers of this type are known. There may be mentioned as forming part of the state of the art a transducer described in a patent application filed by the applicant on the Aug. 11, 1981 and published under the U.S. Pat. No. 2,511,570.
This transducer uses a resilient structure in the form of an embedded plate having at least one incurvation and convered on both its faces with electrodes connected to an electric impedance matching circuit. It is formed from an assembly of elements arranged according to an original principle which confers excellent qualities thereon. However, the relative high number of these elements and the method of assembling them are not satisfactory for high rate and low cost mass production of these transducers.
These considerations led the applicant to file on the Mar. 7th, 1983 patent application filed under the n.degree. 83.93 697 concerning an electroacoustic transducer formed from a limited number of elements which allow the combination of means providing the functions of embedding the vibrating element, internal and external connections, screening, acoustic filtering and protection against damp and dust. However, for reasons of electric insulation and accuracy during mounting this transducer requires an insulating jacket of a more or less complicated shape depending on the quality required for the transducer. The presence of this jacket and positioning thereof leads to a high cost price of this type of transducer.
In order to overcome these drawbacks, the invention provides an electroacoustic transducer with a piezoelectric diaphragm whose main elements are designed in an original way so as to avoid the need to use an insulating jacket and so as to efficiently provide the functions of embedding the vibrating element, of electric connections and acoustic filtering.